CompactChain:An Efficient Stateless Chain for UTXO-model Blockchain

We propose a stateless blockchain called CompactChain, which com-pacts the entire state of the Unspent Transaction Output (UTXO) based blockchain systems into two RSA accumulators-Transaction Output (TXO) commitment (representing TXO set), and Spent Transaction Output (STXO) commitment (representing STXO set). In this work, we discuss three algorithms-(i) To update the TXO and STXO commitments by the miner along with a valid proof; (ii) To prove the transaction’s validity by providing a membership witness in TXO commitment and non-membership witness against STXO commitment for a coin being spent by a user. The user also updates the witness for the coin that is not yet spent; (iii) Validator verify the above proofs created by the miner and user. The experimental results evaluate the performance of the CompactChain in terms of time consumed by a miner to update the commitments, time consumed by a validator to verify the commitments and validate the transactions. We compare the performance of CompactChain with the existing state-of-art works on stateless blockchains. CompactChain shows a reduction in commitments update complexity and transaction witness size without compromising the system throughput in terms of transactions per second (TPS).